title: End-tidal versus manually-controlled low-flow anaesthesia.
abstract: During low-flow manually-controlled anaesthesia (MCA) the anaesthetist needs constantly adjust end-tidal oxygen (EtO2) and anaesthetic concentrations (EtAA) to assure an adequate and safe anaesthesia. Recently introduced anaesthetic machines can automatically maintain those variables at target values, avoiding the burden on the anaesthetist. End-tidal-controlled anaesthesia (EtCA) and MCA provided by the same anaesthetic machine under the same fresh gas flow were compared. Eighty patients were prospectively observed: in MCA group (n = 40) target end-tidal sevoflurane (1%) and EtO2 concentrations (≥ 35%) were manually controlled by the anaesthetist. In EtCA group (n = 40) the same anaesthetic machine with an additional end-tidal control feature was used to reach the same targets, rendering automatic the achievement and maintenance of those targets. Anaesthetic machine characteristics, amount of consumed gases, oxygen and sevoflurane efficiencies, and the amount of interventions by the anaesthetist were recorded. In EtCA group EtAA was achieved later (145 s) than in MCA (71 s) and remained controlled thereafter. Even though the target expired gas fractions were achieved faster in MCA, manual adjustments were required throughout anaesthesia for both oxygen and sevoflurane. In MCA patients the number of manual adjustments to stabilize EtAA and EtO2 were 137 and 107, respectively; no adjustment was required in EtCA. Low-flow anaesthesia delivered with an anaesthetic machine able to automatically control EtAA and EtO2 provided the same clinical stability and avoided the continuous manual adjustment of delivered sevoflurane and oxygen concentrations. Hence, the anaesthetist could dedicate more time to the patient and operating room activities.
authors.affiliation: Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University School of Medicine, Strada di Fiume 447, 34139, Trieste, Italy, u.lucangelo@fmc.units.it.
authors.forename: Umberto
authors.initials: U
authors.lastname: Lucangelo
authors.forename: Giuliana
authors.initials: G
authors.lastname: Garufi
authors.forename: Emanuele
authors.initials: E
authors.lastname: Marras
authors.forename: Massimo
authors.initials: M
authors.lastname: Ferluga
authors.forename: Federica
authors.initials: F
authors.lastname: Turchet
authors.forename: Francesca
authors.initials: F
authors.lastname: Bernabè
authors.forename: Lucia
authors.initials: L
authors.lastname: Comuzzi
authors.forename: Giorgio
authors.initials: G
authors.lastname: Berlot
authors.forename: Walter A
authors.initials: WA
authors.lastname: Zin
mesh_terms: D000368:Aged; D000769:Anesthesia, Inhalation / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000032:analysis; D004360:Drug Therapy, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage* / Q000032:analysis*; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010101:Oxygen Consumption / Q000187:drug effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000077149:Sevoflurane; D013990:Tidal Volume / Q000187:drug effects*; D016526:Workload
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane